Amino Acids Flashcards
What are amino acids?
Organic compounds containing amine [-NH2], carboxyl [-COOH], and a side chain [R group].
Major elements include carbon, hydrogen, nitrogen, and oxygen.
How many amino acids are known?
About 500 amino acids are known, though only 20 appear in the genetic code.
What is the need for the classification of amino acids?
It provides a grouping between the 20 amino acids, aiding biochemists in understanding their functions.
How can amino acids be classified?
Based on:
* R group
What are simple amino acids?
Amino acids with no functional group in their side chain.
Examples include glycine, valine, alanine, leucine, isoleucine.
What are hydroxy amino acids?
Amino acids that have a hydroxyl group in their side chain.
Examples include serine and threonine.
What defines sulfur-containing amino acids?
Amino acids that have sulfur in their side chain.
Examples include cysteine and methionine.
What are aromatic amino acids?
Amino acids that have a benzene ring in their side chain.
Examples include phenylalanine and tyrosine.
What characterizes acidic amino acids?
Amino acids that have a carboxyl group in their side chain.
Examples include aspartic acid and glutamic acid.
What defines basic amino acids?
Amino acids that contain an amino group in their side chain.
Examples include lysine and arginine.
What are the properties of amino acids?
Physical properties include:
- Melting point above 200°C
- Soluble in polar solvents
- Optical isomers due to asymmetric α-carbon atoms.
What happens during the decarboxylation of amino acids?
They form corresponding amines.
Examples include histidine to histamine.
What occurs when amino acids react with alcohols?
Esterification occurs, forming esters that are volatile.
What are essential amino acids?
Amino acids that cannot be synthesized by the body and must be obtained from food.
Examples include arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
What are non-essential amino acids?
Amino acids that can be synthesized by the human body.
Examples include alanine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine.
What are the properties of amino acids in terms of solubility?
Amino acids are soluble in polar solvents and insoluble in non-polar solvents.
Hydrophobic Amino Acids
*side chains (R groups) are nonpolar, meaning they do not interact well with water
- Alanine (Ala, A)
Valine (Val, V)
Leucine (Leu, L)
Isoleucine (Ile, I)
Phenylalanine (Phe, F)
Tryptophan (Trp, W)
Methionine (Met, M)
Proline (Pro, P)
Glycine (Gly, G)
Polar Neutral Amino Acids
*side chains that can form hydrogen bonds with water but do not carry a charge at physiological pH.
Alanine (Ala, A)
Valine (Val, V)
Leucine (Leu, L)
Isoleucine (Ile, I)
Phenylalanine (Phe, F)
Tryptophan (Trp, W)
Methionine (Met, M)
Proline (Pro, P)
Tyrosine (Tyr, Y)
(-) Charged Amino Acids
acidic amino acids, have side chains that carry a negative charge at physiological pH (7).
This is due to the presence of a carboxyl group (-COOH) in their side chain that dissociates to form a carboxylate anion (-COO⁻).
Aspartic acid (Asp, D)
Glutamic acid (Glu, E)
(+) Charged Amino Acids
basic amino acids, have side chains that carry a positive charge at physiological pH (7).
This is due to the presence of amino groups (–NH2) in their side chains, which can accept protons and become positively charged.
Lysine (Lys, K)
Arginine (Arg, R)
Histidine (His, H)
